1. Field of the Invention
This invention relates in general to a pneumatic animal stunner for use in livestock/slaughterhouse operations and more specifically to the catch system for holding and releasing the stunning rod, the compressed air supply used to retract the stunning rod between operation cycles, and the handles used by the operator to hold the stunner.
2. Description of Related Art
In livestock production plants, it is important to stun and disable an animal for processing. Although numerous methods have been used to stun livestock, captive bolt mechanisms have proven to be the most efficient, inexpensive, and humane way to disable the animal. Particularly, pneumatic captive bolt devices have been used in this capacity.
U.S. Pat. No. 6,135,871 and U.S. Patent Publication No. 2004/0209562, the disclosures of which are hereby incorporated by reference, disclose pneumatic animal stunners that, among other things, include a physical catch for the piston that drives the stunning rod.
FIGS. 1 and 2 show a prior art catch arrangement for a stunner in which stunning rod 1 extending rightward (forward) from a piston 2 has a leftward (rearward) end with outwardly extending lips 3 that may be alternately held and released by inward extending lips at the end portion 4a of a catch 4. At a central portion of the body of catch 4 is an inwardly extending flange 4b which is pivotable about an outwardly extending flange 6a of catch pivot post 6. A catch piston 5 includes an inner bore 5a at a forward end, an inner bore 5c at a rearward end, and a relief portion 5b between the two. In the hold position of FIG. 1, the catch piston 5 is slid longitudinally rearward so that forward inner bore 5a contacts moves catch forward end 4a toward and into engagement with stunning rod lips 3, at the same time that rearward inner bore 5c contacts the outer surface of catch rearward end 4c. In the release position of FIG. 2, the catch piston 5 is slid longitudinally forward so that forward inner bore 5a moves forward of catch forward end 4a, and the relief portion 5b permits catch forward end 4a to move outward and out of engagement with stunning rod lips 3 as the flange 4b of catch 4 pivots about catch post pivot flange 6a. At the same time, catch piston rearward inner bore 5c slides forward and then moves out of contact with the outer surface of catch rearward end 4c. Upon release of the stunning rod lips, compressed air behind piston 2 moves stunning rod 1 forward to stun the animal.
The catch and other components of such prior designs function well, but in operation some of its components are subject to sliding engagement with other components, and therefore interference and/or wear, which causes drag and/or requires periodic replacement of such components.
Compressed air usage by prior art stunners is also an issue, since excess air volume needed for each stunner cycle increases costs of operation. Additionally, the operator is subject to fatigue when using the stunner repeatedly, due to the shock of the stunning rod projection and retraction in each operation cycle.